(a) Field of the Invention
The invention relates to an image detection method and device, particularly to a consecutive thin edge detection system and a consecutive thin edge detection method for enhancing color filter array image.
(b) Description of the Related Art
In general, consumer electronics using a sensor for image acquisition such as digital cameras, video recorders, multimedia mobile phones, surveillance systems, video phones usually use a Bayer color filter array (Bayer CFA) covered on a sensor to record red, green and blue color information simultaneously to achieved the purpose of cost reduction. As shown in FIG. 1, in a Bayer color filter array BCFA, each position of a pixel records a color intensity of a kind of color. As shown in the figure, the position of R pixel records red color intensity and for example, on the right-hand side of the figure, the R spectrum filter only allows red light passing through to the pixel sensor cell Sens; the position of G pixel records green color intensity and for example, on the right-hand side of the figure, the G spectrum filter only allows green light passing through to the pixel sensor cell Sens; and the position of B pixel records blue color intensity and for example, on the right-hand side of the figure, the B spectrum filter only allows blue light passing through to the pixel sensor cell Sens. Therefore, consumer electronics may process an obtained raw Bayer CFA image via a color interpolation algorithm for missing color components to generate a full-color image.
It should be noted that the color interpolation algorithm includes analyzing image structure and color content so that the calculation result has critical impact on the final output image quality.
An edge detection method is usually the most effective and highly complicated step in color interpolation algorithm. If the edge direction of an image is not correctly determined by the edge detection method, the consecutive thin edge of an image is apt to appear significant distortion like maze pattern and false color. For example, as shown in FIG. 2, an ISO 12233 test chart is usually used to evaluate color interpolation efficiency. An instance of a test result including a maze pattern due to an incorrect edge direction determination is shown in spectra 5, 6, and 7.